Research On Modular Three-phase AC/DC Converter With High Power Factor

The wide application of the power electronics equipments produces a great deal of power harmonic. Active power factor correction(APFC) technique is an effective way to increase power factor and reduce harmonic current. Single-phase APFC technique is mature in recent years, but three-phase APFC technique is usually applied in medium and high power applications. Three-phase APFC can be divided into three-phase two-stage APFC and three-phase single-stage APFC according to the structure. Three-phase single-stage APFC has been an important researching orientation,which has the advantages such as high power density, simple structure and high efficiency compared to three-phase two-stage APFC. A modular three-phase AC/DC converter with high power factor is the subject of this paper, several problems such as topology, mathematical model and conrol strategy are addressed.The modular three-phase AC/DC converter with high power factor proposed in this paper can realize the function such as power factor correction, electronic iaolation between the input and outpue sides and output oltage regulation.This paper firstly introduces the topology of the modular three-phase AC/DC converter, which is made up by three single-phase full-bridge circuit connected by magnetic modular transformer. Then the magnetic modular transformer is carried on theoretical analysis. In this base, problems of converters such as mechanism of power factor correction and working modes are analyzed in details. The cycle swich average model and small signal model are established according to the steady equation of the converter. The system simulation model is built in Matlab/Simulink, and the simulation results show that the mathematic model is correct and the strategy is feasible.The designing methods of each parameter in the main circuir are given in the paper. The control system chooses the Freescale's DSP chip MC56F8346 as the core of the system, and the hardware and software design of the system are completed. A 15 k W prototype is built to be exprimentied and confirmed. The experimental results show that the conveter has the function of power factor correction and meet the design requirement, which confirms that the conveter has a certain application prospect in the medium and high power application.